Operation - Yoshitake GP-1000 Installation & Operation Manual

4. Operation

The pressure-reducing valve reduces pressure by the throttling the valve. The valve is composed of the
main valve and main valve seat for throttling, and adjusting spring, diaphragm, pilot valve, and piston
for pressure sensing and activation.
(1) When the pressure-reducing valve is mounted correctly, releasing the compression of adjusting
spring [8] allows the spring to close main valve [11] and pilot valve [19]. Slowly open the gate valve
and allow the high-pressure fluid to flow in. Inlet pressure is applied to the downside of the main
valve. High-pressure fluid passes through strainer [28] via inlet pressure passage [42] to also apply
inlet pressure to the downside of the pilot valve.
(2) Turing adjusting screw [9] clockwise compresses the spring, which flexes diaphragm [5] to open the
pilot valve.
(3) Inlet pressure via inlet pressure passage and pilot valve enters the upside of the piston. The pressure
overrides the pressure on the downside of the main valve and the load of main valve spring[13], to
open the main valve. The fluid then begins to flow from the inlet side.
(4) Reduced pressure is led to diaphragm chamber [44] via reduced pressure sensing port [43]. The
diaphragm receives the reduced pressure to be balanced with the adjusting spring load, and control
the pilot valve travel.
(5) The change of pilot valve travel changes the flow rate of fluid to the upside of the piston, and
controls the main valve travel to obtain appropriate reduced pressure.
No.
1
5
8
9
11
12
13 Main valve spring
14
15
19
20
28
42 Inlet press. passage
43 Reduced press. Sensing port
44 Diaphragm chamber
-3-
Parts name
Body
Diaphragm
Adjusting spring
Adjusting screw
Main valve
Main valve seat
Piston
Cylinder
Pilot valve
Pilot valve seat
Strainer
■EPDT-081a■